wilson



March 1964 w. J. NEUHAUSER ETAL 7,

DUAL-ADHESIVE SPLICING SYSTEM Filed Feb. 10, 1960 ifil llllllllllllzINVENTORS. WILL/AM J. NEUHAUSER CALVIN L. WILSON EARL M T/LLER WQWUnited States Patent 3,127,303 DUAL-ADHESIVE SPLICING SYSTEM William J.Neuhauser, Jefferson County, Calvin L. Wilson, Louisville, and Earl M.Tiller, Jefferson County, Ky., assignors to Reynolds Metals Company,Richmond,

Va., a corporation of Delaware Filed Feb. 10, 1960, Ser. No. 7,802 6Claims. (Cl. 161-39) This invention relates to splicing foil, andparticularly aluminum foil strip which is subsequently wound on to aroll and annealed before being laminated and printed.

Foil strip occasionally breaks during the rolling operations, and it isthen conventional to trim the broken ends and splice them together inabutting relation by application of adherent tape to one or both sidesof the break, before resuming operations. A conventional splicing tapeis a ribbon of aluminum foil with adhesive on one side to grip thespliced ends of the foil strip. The roll of foil containing the spliceis then usually annealed at temperatures of about 500 to 800 F., andafter annealing the roll of foil is unwound preliminary to furtheroperations, such as converting or laminating. For this reason, anadhesive is required which will not lose its holding quality in thattemperature range.

Difficulty, including further breakage, is often encountered when theannealed roll is unwound, because of adhesion between the spliced jointsand the surfaces of adjacent convolutions of the foil. Although the foiltape is impervious to penetration by the adhesive, pressure sometimescauses the adhesive on the tape to bleed beyond the edges of the tapewhen the spliced strip is wound in a roll, and this small amount ofadhesive is enough to stick to adjacent convolutions of the foil strip,causing the foil strip to break when the roll is unwound after theannealing operation. It is conventional to dust the spliced strip withtalc in order to minimize such unwanted sticking, but this is not alwayseffective, and the tendency of the talc to spread as much as two orthree feet from the spliced joint increases the amount of scrap whichmust eventually be discarded when the spliced joint is cut away duringfinal inspection.

While various heat-activated adhesives have been tried for this purpose,certain problems have developed. When wide strips are spliced, theadhesive necessarily extends over a substantial area. It was found to bevery difficult to apply heat evenly over such area without producingwrinkles, and subsequent interference with winding and unwindingoperations.

In addition, adhesives having desired thermal properties were foundfrequently to lack sufiicient tackiness at room temperature to retaintheir placement prior to the application of heat and pressure.

In accordance with the present invention, these problems are minimizedor eliminated by a novel splicing tape which employs a duality ofadhesive materials. One material, which is tacky and effective withoutthe application of heat or great pressure, is disposed in a narrow bandcentrally of the tape. A second material, requiring pressure and/ orheat to develop its adhesive quality, is disposed in spaced narrow bandswhich straddle the first material. By this combination, the tape is heldsecurely in place initially by the first adhesive. The subsequentapplication of heat from the annealing operation functions to set up thesecond material, providing a permanent bond, and establishing barrierseffective to preclude bleeding out of the first adhesive. The result isa splice free from wrinkles, due to the lesser areas of heat-sensitiveadhesive; and the previously required talc dusting step becomesunnecessary.

For better understanding of the invention, reference is made to theaccompanying drawing, in which there is shown, for puropses ofillustration only, a present preferred embodiment of the invention.

In the drawing:

FIG. 1 is a semi-diagrammatic longitudinal plan view of a strip of foilhaving a taped splice;

FIG. 2 is an enlarged cross-sectional view of the spliced portion of thestrip, taken on line 22 of FIG. 1; and

FIG. 3 is a fragmentary plan view of the adhesive side of a tape inaccordance with the present invention.

Referring now to the drawing, a strip 10 of aluminum foil (FIG. 1) iscustomarily rolled in sizes of up to about 60 inches in Width andvarying in thickness from 0.00025 inch to 0.001 inch, and wound into alarge roll, which is then annealed preparatory to slitting, laminating,printing and other operations. The strip is sometimes torn across itswidth during rolling, and the torn ends are rejoined by a splice. Asshown in FIG. 1, the strip 10 is severed along the line 12 where thetrimmed ends are abutted and secured together by splicing tapes 14.After splicing, the rolling and winding of the strip 10 on the roll iscompleted. The length of the tape 14 is approximately the same as thewidth of strip being spliced, although it may be made greater, tofacilitate subsequent inspection of the roll and cutting out of thespliced joint where that is desired.

Two of the tapes 14 are preferably applied on opposite sides of the foilstrip, as shown in FIG. 2. Each of the tapes 14 comprises a ribbon offoil 16, for example, aluminum foil of 0.00035 inch thickness, andadhesive disposed on one side of the foil ribbon. For purposes ofillustration, FIG. 2 shows the adhesive layers with greatly exaggeratedthickness.

As shown in FIGURE 3, a central band 18 of tacky adhesive is applied tothe foil ribbon 16. For this purpose, a material such as Dow Corning#269 has been found suitable. On either side of band 18 are similarbands 20 of another adhesive, preferably Dow Corning Silicone #993.

The band 18 serves to hold the tape 14 in place, and to temporarilysplice the strip.

After the foil strip has been wound into a roll with the spliced jointwithin the convolutions of the roll, the roll is deposited in anannealing oven. When heat is subsequently applied, the outer bands 20are activated to complete a permanent seal and confine the adhesive ofband 18 (which may flow at the temperature level of the annealingfurnace). The annealed roll is subsequently unwound for use or furtherprocessing, such as laminating to backing paper and then printing. Ithas been found that, by use of the special tape 14, the splice or jointdoes not bleed adhesive; and consequent sticking to adjacentconvolutions of foil is thereby avoided when the roll is unwound.

While the present preferred embodiment and method of practicing theinvention has been described and illustrated, it will be recognized thatthe invention may be otherwise variously embodied and practiced withinthe scope of the following claims.

We claim:

1. A tape for use in splicing metal foil strip comprising a layer offoil, a coating of adhesive which is tacky at room temperature disposedcentrally on said foil layer and extending lengthwise of the tape, andspaced bands of a second adhesive on said layer of foil at either sideof said central coating, said second adhesive being heatresponsive inthe range of temperatures utilized for annealing the foil strip to forma strong bond between said tape and the foil strip being spliced.

2. A foil strip having a splice, said splice comprising separated edgestransversely of a foil strip juxtaposed in substantially abuttingrelation, and at least one splicing tape extending along and overlappingsaid edges and adhering to one side of the foil strip, said tapeincluding a layer of foil having a plurality of adhesive substancesdisposed thereon in generally parallel spaced bands, at least onecentrally disposed band comprising an adhesive which is tacky at roomtemperature, and the outermost bands adjacent the longitudinal edges ofsaid layer of foil comprising adhesive substances which arethermosetting.

3. A spliced foil strip according to claim 2 wherein said foil layer isaluminum foil and the thermosetting adhesive bands of the tape areheat-responsive in the range of temperatures for annealing said foil tocomplete the bond between said tape and said foil strip, whereby saidoutermost bands establish barriers against the flow of said tackyadhesive beyond the edges of said layer of foil and upon the surface ofsaid foil strip.

4. In the art of splicing a strip of metal foil, including the steps oftrimming the edges of a tear in the foil, abutting the trimmed edges andapplying a splicing tape to the foil strip, the improvement whichcomprises initially adhering said tape to the foil with pressuresensitive adhesive which is tacky at room temperature, providing bandsof thermosetting adhesive between said firstmentioned adhesive and thefoil surfaces adjacent the tape, and heating the strip to activate saidthermosetting adhesive and thereby to prevent the flow of saidfirstmentioned adhesive onto the adjacent exposed surfaces of the foil.

5. The method of joining strips of aluminum foil disposed insubstantially abutting relationship comprising the steps of applying asplicing tape on opposite sides of the foil overlapping the opposed endsof said strips, initially adhering said tape to the foil by means of anarrow band of pressure sensitive adhesive which is tacky at roomtemperature but tends to flow at a temperature suflicient to anneal thefoil, and preventing said adhesive from flowing onto the exposedsurfaces of the foil strips by disposing spaced bands of thermosettingadhesive straddling said narrow band of adhesive and heating the stripsto anneal the foil and to establish the holding action of thethermosetting adhesive.

6. The method of splicing aluminum foil in strip form preparatory to theannealing of said foil, comprising the steps of trimming the edges of atear in the foil, juxtaposing the trimmed edges in substantiallyabutting relationship, initially adhering to the foil an aluminum foilsplicing tape on at least one side of the strip and overlapping thetrimmed edges employing an adhesive which is tacky at room temperature,preventing the flow of said adhesive onto the exposed foil surfacesduring subsequent annealing by providing barrier layers of thermosettingadhesive between said first-mentioned adhesive and the edges of saidtape adjacent said surfaces, and annealing the foil in the form of atightly wound coil, the annealing temperature being sufficient toestablish the holding action of said thermosetting adhesive and thebarrier layers thereby preventing sticking between adjacent layers ofthe coil.

References Cited in the file of this patent UNITED STATES PATENTS 693,514 Haberstroh Feb. 18, 1902 852,761 Bodine May 7, 1907 1,217,252VJilliarnson Feb. 27, 1917 2,372,737 Phillips Apr. 3, 1945 2,711,382Smith-Johannsen June 21, 1955 2,975,091 Tobey Mar. 14, 1961

1. A TAPE FOR USE IN SPLICING METAL FOIL STRIP COMPRISING A LAYER OFFOIL, A COATING OF ADHESIVE WHICH IS TACKY AT ROOM TEMPERATURE DISPOSEDCENTRALLY ON SAID FOIL LAYER AND EXTENDING LENGTHWISE OF THE TAPE, ANDSPACED HANDS OF A SECOND ADHESIVE ON SAID LAYER OF FOIL AT EITHER SIDEOF SAID CENTRAL COATING, SAID SECOND ADHESIVE BEING HEATRESPONSIVE INTHE RANGE OF TEMPERATURES UTILIZED FOR ANNEALING THE FOIL STRIP TO FORMA STRONG BOND BETWEEN SAID TAPE AND THE FOIL STRIP BEING SPLICED.